Automated manufacturing processes can be used to quickly and efficiently manufacture materials in mass quantities. For example, silicon-based wafers and solar cells can be manufactured using automated fabrication lines. While such manufacturing processes can yield significant quantities of materials, it is often important to inspect the end product for quality assurance and/or process control because the revenue realized by the fabrication plant is often directly related to the quality of the end product (or material). Therefore, a key factor for high quality manufacturing processes is often a high speed and high precision inspection apparatus for testing and screening the end product of the manufacturing process.
For example, for solar cells, the conversion efficiency (how efficient the PV system is at converting sunlight into electrical energy) often has a direct influence of the output of electrical power. Therefore, solar cell manufacturers want to attain higher conversion efficiency through their fabrication lines, because selling prices are related to conversion efficiency. As a result, solar cell manufacturers can employ an inspection apparatus to test solar cells for sufficient conversion efficiency.
Manufacturers can use computer vision to inspect fabricated materials and/or products. However, many manufactured materials do not have uniform surfaces, which often makes inspection of such materials (e.g., for defects such as cracks) using computer vision difficult. For example, polycrystalline solar cells are often made up of heterogeneous textures and confusing features. Therefore, defects in polycrystalline solar cells, such as cracks, often have a non-uniform appearance (e.g., non-uniform contrast, polarity, width, etc.). Further, portions of such defects can often have very low contrast (e.g., 1-2 gray levels).
Present material inspection systems that are configured to detect hard-to-identify defects often use high-resolution images to expose the defects. However, using high-resolution images is more data-intensive, and therefore requires more time for each inspection.